The most stringent protection of free speech would not protect a man falsely shouting… — Oliver Wendell Holmes, Jr.

The most stringent protection of free speech would not protect a man falsely shouting fire in a theatre and causing a panic... The question in every case is whether the words used are used in such circumstances and are of such a nature as to create a clear and present danger that they will bring about the substantive evils that Congress has a right to prevent.